You may need to update the software. The camera would have included a disk with the software to transfer images from the camera (EOS Utility) and software to browse (Image Browser) and edit (Digital Photo Professional). But that CD would be loaded with software that was current back when the camera was new. As computer operating systems are updated, that software also needs to be updated.
You can find the updates here: http://www.usa.canon.com/cusa/consumer/products/cameras/slr_cameras/eos_rebel_t3i_18_55mm_is_ii_lens...
BTW, you do not have to use Canon's software to transfer images or edit the files. Numerous 3rd party applications can import images from the camera as well.
I typically do not connect my camera to the computer. Instead, I remove the memory card and insert it into a card reader attached to my computer (the transfers are faster that way.)
Tim Campbell
5D III, 5D IV, 60Da
